1. Field of the Invention
This invention relates generally to an optical switch device wherein switching pattern signals are obtained by allowing and disallowing a light from a light source to impinge on a light detector, and more particularly to the optical switch device wherein a fluorescent substance is employed as the light source.
2. Description of the Prior Art
Switch devices wherein a combination of a light-emitting diode and a phototransistor is utilized have been contemplated to replace the switch devices having switch contacts. For example, in one of such switch devices, a light guiding member formed of a plastic material or an optical fiber provides a light passageway for a light between the light-emitting diode and the phototransistor, and a shutter is moved into and out of the light passageway.
According to the above-described switch device, the light-emitting diode is required to be normally held "on." Thus, the prior art switch device employing the light-emitting diode and the phototransistor has a disadvantage in electric power consumption.